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Re: [TowerTalk] Min spacing to 80m yagi ?

To: jim.thom@telus.net, towertalk@contesting.com
Subject: Re: [TowerTalk] Min spacing to 80m yagi ?
From: TexasRF@aol.com
Date: Wed, 6 Oct 2010 08:48:44 EDT
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Jim, wouldn't you think that the 20m yagi would suffer pattern degradation  
while the 80m yagi would be ok?
 
73,
Gerald K5GW
 
 
 
 
In a message dated 10/6/2010 7:35:00 A.M. Central Daylight Time,  
jim.thom@telus.net writes:

How  close can you get a 20m yagi, below a 2-el  80m yagi ? 
I have an  option to use a F-12  Sigma  280-S  shortened 80m yagi
at  the top of the mast, with the F-12  340N  at the bottom of the mast.  
Spacing between the two of them would be  10.5'    If  possible,  I 
would like to sandwich my  F-12  520   [20m yagi]  between the 
80 and 40m yagi.    Apparently, you  can mount any other F-12 HF
yagi within 36"  of the 3-el  340N  yagi.    If I put the 20m yagi
4'  above the 40m yagi...  that would leave  6.5' between the 20m yagi
and the 80m  yagi.   Will this work ??    If it doesn't, one option  is
to remove the 20m yagi.   Another option is  to   place the 80 and 40m
yagi's at right angles to each other [ no 20m yagi at  all] .   I don't 
think this
is required, but would minimize the  total wind load. 

Plan B  would be to replace the 2-el 80m yagi  with a
80m rotary dipole...with dipole inline with 20m/40m booms   below it.  IE: 
dipole
is then at right angles to both yagi's below  it.   Due to  day time height 
restrictions,
the above  options are strictly an after dark scenario.   I don't have any  
software on hand
to model any of the above.

Thanks....  Jim   VE7RF


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